Turbulence is more than blowing hot air. During the baking process, controlling the amount of turbulence, or more correctly convection, refers to the movement of air in the oven chamber and how it impacts the consistency, texture and quality of final products.

It can also be used to decrease bake times and potentially reduce energy.

“A certain amount of air movement is important to help to reduce the boundary layer of moisture on the surface of the product,” said Phil Domenicucci, baking systems specialist, AMF Bakery Systems. “This will help more efficiently release moisture from the product, shorten baking times and will increase oven energy efficiency.”

Specifically, turbulence plays a key role in heat transfer and minimizes air temperature differentials across the bake chamber, noted Jerry Barnes, vice president, Babbco.

“Select applications, however, require ‘dead air’ so as not to skin over the product surface too early in the bake profile,” he said. “For this, we can easily deploy radiant heating methods where needed.”

When baking with convection heat, the transfer of energy into bread products is more efficient than when baking with just radiant heat, observed Ken Johnson, president, Gemini Bakery Equipment. Bake chamber temperatures in a convection zone of an oven are cooler than those of a radiant-only zone.

He added turbulence in a Gemini/Werner & Pfleiderer indirect gas-fired tunnel oven is flow-adjustable and can be from top-to-bottom or bottom-to-top. Another advantage is a more consistent product bake and uniform color, especially for panned breads. 

On the other hand, baking panned breads in radiant heat-only ovens can produce weak product sidewalls and inconsistent color, such as lighter color bands around the sides of loaves.

Moreover, areas of the product that are farther away from the radiant heat source are exposed to less energy.

As a result, Mr. Johnson said, bottoms of panned bread that are nearest to where the heat energy is radiating from might be properly baked, but the sides of the loaves farther away from the radiant heat source can be underbaked.

Bakeries also use turbulence systems for baking rye bread and other types requiring higher energy density levels and even surface colorings, said Nicola Menardo, president of TP Food Group, North America.

The company measures the “turbulence limit” to ensure the airflow won’t damage the product instead of improving its quality and consistency.

Overall, ovens with strong convective currents provide better heat transfer as well as the ability to recycle leftover heat by recirculating process air, said Tyler Martin, R&D engineer, baking systems, Reading Bakery Systems (RBS).

However, some products, such as crackers and cookies, cannot handle strong convective currents at the beginning of the bake cycle and will require an oven zone that uses more radiant and conductive heat. 

In rack ovens, baking with turbulence can generate immense advantages, especially for products like buns with short baking times, said Christian Benedikt, group leader, oven design for Koenig Bakery Systems.

Bakeries can bake more products at the same time and with up to 30% or 40% less energy compared to ovens with radiant heat, he added.